Specific Carbohydrate Diet and Autism

The Specific Carbohydrate Diet (SCD) is a nutritional diet created by Dr. Sidney V. Haas, which eliminates and restricts the use of complex carbohydrates (disaccharides and polysaccharides) and eliminates refined sugar, all grains and starch from the diet.
Elaine Gottschall a biochemist popularized the diet and also promotes its use in reducing the symptoms of autism.

Gottshall’s theory is that there is an overgrowth of harmful bacteria in the body due to damage to microvilli in the body. These microvilli are found in the stomach, are damaged and lack the ability to break down specific types of complex carbohydrates. More recent studies confirmed the correlation between Gastro intestinal disturbances and autism symptoms.

Autism spectrum disorders (ASD) are defined by impairments in verbal and non-verbal communication, social interactions, and repetitive and stereotyped behaviors. In addition to these core deficits, previous reports indicate that the prevalence of gastrointestinal (GI) symptoms ranges widely in individuals with ASD, from 9 to 91% in different study populations.

Macroscopic and histological observations in ASD include findings of ileo-colonic lymphoid nodular hyperplasia, enterocolitis, gastritis, and esophagitis. Associated changes in intestinal inflammatory parameters include higher densities of lymphocyte populations, aberrant cytokine profiles, and deposition of immunoglobulin (IgG) and complement C1q on the basolateral enterocyte membrane. Reported functional disturbances include increased intestinal permeability, deficient enzymatic activity of disaccharidases, increased secretin-induced pancreatico-biliary secretion, and abnormal fecal Clostridia taxa. Some children placed on exclusion diets or treated with the antibiotic vancomycin are reported to improve in cognitive and social function. Furthermore, a recent study found a strong correlation between GI symptoms and autism severity.

The intestinal mucoepithelial layer must maximize nutritional uptake of dietary components while maintaining a barrier to toxins and infectious agents. Although some aspects of these functions are host-encoded, others are acquired through symbiotic relationships with microbial flora. Dietary carbohydrates enter the intestine as monosaccharides (glucose, fructose, and galactose), disaccharides (lactose, sucrose, and maltose), or complex polysaccharides. Following digestion with salivary and pancreatic amylases, carbohydrates are further digested by disaccharidases expressed by absorptive enterocytes in the brush border of the small intestine and transported as monosaccharides across the intestinal epithelium. Although humans lack the glycoside hydrolases and polysaccharide lyases necessary for cleavage of glycosidic linkages present in plant cell wall polysaccharides, oligosaccharides, storage polysaccharides, and resistant starches, intestinal bacteria encoding these enzymes expand our capacity to extract energy from dietary polysaccharides. As an end product of polysaccharide fermentation, bacteria produce short-chain fatty acids (butyrate, acetate, and propionate) that serve as energy substrates for colonocytes, modulate colonic pH, regulate colonic cell proliferation and differentiation, and contribute to hepatic gluconeogenesis and cholesterol synthesis. Intestinal microbes also mediate postnatal development of the gut mucoepithelial layer, provide resistance to potential pathogens, regulate development of intraepithelial lymphocytes and Peyer’s patches, influence cytokine production and serum immunoglobulin levels, promote systemic lymphoid organogenesis, and influence brain development and behavior.

When following SCD, one removes all complex sugars: all sugars except honey and fruit sugar. This includes the removal of maple syrup, cane sugar, agave nectar, brown rice syrup and more. It also involves the removal of all starches; all grains, potatoes and sweet potatoes. This diet allows meat, fish, nuts and seeds, certain beans, all non-starchy vegetables, fruit, fats and oils.

This diet is not a low carbohydrate diet, it is a specific carbohydrate diet. The goal is not to restrict all carbohydrates (such as with the Atkins diet), but to eliminate the carbohydrates that require enzymes and good gut function to process—such as disaccharides including sugars as described above and polysaccharides in starchy foods. The diet allows fruit, all non-starchy vegetables such as broccoli, kale, cauliflower, even sweeter vegetables including carrots, winter squash, and beets, and certain beans—and it’s important to get some of these carbohydrates (monosaccharides) in a form that allows for immediate absorption.

By removing complex starches, this diet supports good health and improvements with autism. Pathogenic microbes such as yeast and bad bacteria give off toxins that affect the brain. By removing the sugars and starches that feed these bugs, the toxins that overwhelm the brain and liver are reduced. By reducing the population of pathogenic bugs, as well as poorly digested starches/sugars, and inflammatory proteins, digestion can improve, leading to greater absorption of nutrients that support brain chemistry and function. The removal of gluten, casein, and soy with SCD reduces the opiates that can be produced from improper digestion. Also, remember to add good nutrition and nourishing foods to supply needed nutrients.

Foods to avoid on SCD
• No grains or corn
• No potatoes (white or sweet)
• No soy products
• No sugars except honey
• No cornstarch, arrowroot powder, tapioca, agar-agar or carrageenan
• No pectin in jams
• No chocolate or carob
• No baking powder (baking soda OK)

Foods to Eat
• Vegetables (non-starchy)
• Fruit
• Fruit juice not from concentrate
• Honey
• Meat
• Eggs (if tolerated)
• Nuts/seeds and nut milks (if tolerated)
• Certain beans
• Ghee

Enzymes are very helpful with diet. Frequently, elimination diets (anything that eliminates foods such as GFCF, SCD) work by eliminating a food that can’t be broken down by current digestive function—this is where enzymes are helpful. When someone cannot tolerate gluten, it is often because the partially broken down protein creates an inflammatory response or opiates. One of the functions behind SCD is removal of the starches and sugars that are not properly broken down—due, in part, to insufficient enzymes. By taking enzymes, these proteins and carbohydrates are broken down into their useable component, instead of feeding the inflammatory cycles.

Enzymes are helpful, but they are not a substitute for diet. In the case of the Specific Carbohydrate Diet, enzymes can help break down foods, proteins, carbs, and fats that can cause and inhibit digestion. Enzymes also support good health by helping to breakdown foods for better absorption of nutrients


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